The West African country was the site where the original Ebola chain of transmission began two years ago. A menacing disease, it spread to Liberia, Sierra Leone and seven additional countries. According to the New York Times, the December 2013 Ebola outbreak led to its largest epidemic in history—taking more than 11,300 lives worldwide.

WHO notes that over 40 days have passed since the last person confirmed to have Ebola tested negative for a second time (which was after an incubation period). Further, Guinea is under a 90-day surveillance period to identify and treat new cases of the virus.

Still, WHO doctors remain hopeful.

“This is the first time that all three countries—Guinea, Liberia and Sierra Leone—have stopped the original chains of transmission that were responsible for starting this devastating outbreak two years ago,” says Dr. Matshidiso Moeti, WHO regional director for Africa.